An increasing number of passenger vehicles manufactured today are equipped with supplemental inflatable restraints for vehicle occupants; these are commonly known as air bags. The air bag for the front seat passenger is normally located in a storage compartment mounted in the vehicle dash board.
The dash board normally comprises a metal support structure covered by decorative panel comprising a rigid metal or plastic backing plate on which is mounted a resilient foam pad having a flexible plastic outer skin covering. The dash board support mounts the air bag storage compartment and incorporates a door formed in the decorative panel to cover this storage compartment. This door is normally rectangular and is mounted in an opening in the surrounding panel area so that it can be swung open by the deploying air bag upon inflation.
Alternatively, the air bag door can comprise an integral portion of the foam and skin layers that is ripped open by a cutter mounted on the door backing plate upon air bag inflation. In another arrangement, the skin includes a tear seam line of weakened panel material along three sides of the door. This tear seam is fractured by the inflating air bag so that the door swings open about its fourth side, which functions as a hinge, to enable the air bag to properly deploy.
It is essential that the door pivot out of the way of the deploying air bag and remain attached to the dash board upon opening. If the door should separate from the dash board under the explosive force of the deploying air bag, it would become a dangerous missile. If the door does not reliably pivot out of the way of the deploying air bag, it could affect air bag deployment and effectiveness.
Many different arrangements have been utilized in an attempt to assure that the door does indeed pivot out of the way upon opening, while maintaining the door attached to the panel.
One such arrangement is shown in U.S. Pat. No. 4,925,209 to Sakurai in which the metal door support is doubled over and bolted to the dash board structure at spaced intervals. In case the doubled door metal should fail, a loop is formed in the doubled metal fold and a rod is placed therein to physically engage the bolts to prevent door separation.
Other arrangements form the door from an integral flap of the dash board metal support structure. Yet others provide tethers to prevent separation.
It is desirable for the door to hinge open about a predictable hinge line and to open completely while remaining attached to the dash board, so that it not restrict or otherwise affect deployment of the air bag.
It is also desirable to attach the door to the surrounding dash board so that it will tear about a predictable tear seam line upon air bag inflation.